1. Field of the Invention
The presently disclosed subject matter relates to a three-dimensional imaging device and an autofocus adjustment method for the three-dimensional imaging device, and specifically relates to a technology for efficiently searching for in-focus positions of two imaging units and enhancing focusing accuracy as well.
2. Description of the Related Art
Conventionally, a number of three-dimensional imaging devices including two imaging units have been proposed (see, Japanese Patent Application Laid-Open No. 2005-045511 and Japanese Patent Application Laid-Open No. 2006-162990). While the three-dimensional imaging device can perform three-dimensional imaging which images the same subject from different viewpoints using the two imaging units, it can perform super-wide-angle panoramic imaging, imaging in different sensitivities for the respective two imaging units, and the like.
According to the one performing the above-mentioned three-dimensional imaging using the two imaging units, the two imaging units are arranged at the positions corresponding to a right eye and a left eye, being given parallax, and based on image signals outputted from the both imaging units, an image signal for the right eye and an image signal for the left eye are generated by signal processing units at their downstream, respectively. Inputting the image signal for the right eye and the image signal for the left eye thus generated by the signal processing units of the three-dimensional imaging device into a display device having a display screen capable of three-dimensional display gives a three-dimensional image on the display screen.
Incidentally, a number of digital cameras perform so-called contrast AF (Auto Focus) as focus adjustment, which is adjustment of an in-focus position, where autofocus adjustment means which is built inside allows a focus lens in an imaging optical system to move within a predetermined search range, detects contrast of an image, which is being imaged, during the period of moving the focus lens, and allows the focus lens to move to the in-focus position (lens position) at which the contrast is at its maximum.
As to the three-dimensional imaging device in the above-mentioned Japanese Patent Application Laid-Open No. 2005-045511, for the reason that the two imaging units take the same subject, the contrast AF is performed only in one imaging unit, and the result of the contrast AF is reflected to the other imaging unit. Thereby, time required for the contrast AF of the imaging device having two imaging units is reduced. Moreover, Japanese Patent Application Laid-Open No. 2006-162990 proposes a technology for three-dimensional imaging devices that AF search is performed by moving focus lenses included in the both imaging units in directions reverse to each other and that the in-focus positions of the both imaging units are determined using the AF search result of the imaging unit that has detected the in-focus position earlier out of the both imaging units.